A power unit equipped with a dry sump type lubricating device includes an oil tank for storing oil pumped by a scavenging pump. The oil tank is generally defined within a unit case. The power unit having a unit case cover includes the oil tank defined between a unit case and the unit case cover (e.g., see Japanese Patent Laid-Open No. 2001-73736).
In Japanese Patent Laid-Open No. 2001-73736, a unit case is formed with a crank chamber and a transmission chamber. The crank chamber journals a crankshaft to direct the traveling direction of a vehicle. The transmission chamber is disposed on the side of the crank chamber so as to journal a shift shaft. The unit case is divided into two portions, i.e., a front case and a rear case, in a back-and-forth direction. The front case is covered by a front case cover from the front. The oil tank is formed between the front case cover and the front case and between the front case and the rear case.
Thus, the oil tank is formed to protrude laterally outwardly from a shift chamber so as to avoid the shift chamber, a shift clutch and the like as well as the crank chamber. This enlarges the entire power unit.
The present invention has been made in view of the foregoing and it is an object of the invention is to provide a power unit equipped with a dry sump type lubricating oil device that can be reduced in size and in pump loss by disposing an oil tank at an appropriate position outside a unit case cover.